Electronic devices such as disk drives are designed to operate within certain temperature ranges. However, when operating, devices such as disk drives may generate heat. If enough heat is generated to cause one of the disk drives to operate outside of its operational temperature range, problems may occur. For example, in some cases, increased temperature may cause a device to malfunction or behave erroneously. Sometimes, increased heat may even damage the electronic devices.
Historically, individual disk drives have not been particularly troublesome heat generating components. Most disk drives are adequately cooled using passive cooling techniques or by using one or more fans. Thus overheating problems rarely occur. As disk drives have become faster, however, their heat generation has increased. For example, as access speeds have increased, the spindle motors have become faster and more powerful. As a result, the spindle motors have also begun generating more heat. Thus, the cooling of individual disk drives is becoming much more of a concern than it has been in the past.
Another related cooling concern arises when multiple disk drives are placed close together within an enclosure. With rising data storage needs and decreasing storage media costs, more storage media such as disk drives may be included in enclosures. For example, a large number of disk drives may be set up as a RAID (Redundant Array of Inexpensive/Independent Disks) system. Alternately, a large number of disks may be arranged in a MOD (Just a Bunch Of Disks) configuration, which is any group of disks that are not set up in any specific RAID configuration. A common engineering goal is to achieve high-density packaging of disk drives in an enclosure so that the overall storage system takes up a minimal amount of space. However, this goal is often hindered by the need to cool the disk drives. In many cases, the probability of heat-related problems increases as disk drives are packaged more closely together. For example, the ability to transfer heat away from a hard disk drive may be reduced as the airflow over that disk drive is reduced.
When multiple disk drives are packaged closely together, the airflow over some of the disk drives may be blocked or constrained by the surrounding disk drives. Additionally, the combined heat generation from all of the disk drives may create a much hotter area than each disk drive would create individually. Thus, the disk drives in a high-density arrangement are more likely to be in a hotter environment due to the heat generation of neighboring drives. Furthermore, the airflow in a chassis may not be able to transfer as much heat away from the disk drives because neighboring drives may be blocking airflow for such drives. As a result, disk drives in a high-density arrangement are more likely to develop heat-related problems.